Many functions of modern devices in automotive, consumer and industrial applications, such as converting electrical energy and driving an electric motor or an electric machine, rely on power semiconductor devices. For example, Insulated Gate Bipolar Transistors (IGBTs), Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) and diodes, to name a few, have been used for various applications including, but not limited to switches in power supplies and power converters.
A power semiconductor device usually comprises a semiconductor body configured to conduct a load current along a load current path between two load terminals of the device. Further, the load current path may be controlled by means of an insulated electrode, sometimes referred to as gate electrode. For example, upon receiving a corresponding control signal from, e.g., a driver unit, the control electrode may set the power semiconductor device in one of a conducting state and a blocking state.
In some cases, the gate electrode may be included within a trench of the power semiconductor device, wherein the trench may exhibit, e.g., a stripe or closed polygonal cell configuration or a needle configuration.
Further, such trench occasionally includes more than only one electrode, e.g., two or more electrodes that are arranged separately from each other and sometimes also electrically insulated from each other. For example, a trench may comprise both a gate electrode and a field electrode, wherein the gate electrode can be electrically insulated from each of the load terminals, and wherein the field electrode can be electrically connected to one of the load terminals.
A power semiconductor device is usually configured to conduct a forward current along a forward current path between two load terminals of the device in a forward-conducting state. The load current path may be controlled by means of the first electrode, sometimes referred to as gate electrode. For example, upon receiving a corresponding control signal from, e.g., a driver unit, the gate electrode may set the power semiconductor device in one of the forward-conducting state and the forward-blocking state.
Occasionally, such a power semiconductor device is further configured to conduct the reverse current between the two load terminals in a direction opposite to the one of the forward current. For example, in the case of reverse conducting IGBTs (RC-IGBTs), such a reverse conduction capability may be realized by providing a reverse-conducting path via a body diode included in the semiconductor body that is forward-biased in the reverse-conducting state of the semiconductor device.
It is generally desirable to keep switching losses that occur upon switching of such devices between the reverse-conducting state and the forward-conducting state low. To this end, it may be desirable to keep an emitter efficiency, e.g. an anode emitter efficiency, of the body diode of the device comparatively low in the reverse-conducting state.